12.5 nm base pseudomorphic heterojunction bipolar transistors achieving fT=710 GHz and fMAX=340 GHz -: art. no. 252109

The pseudomorphic collector structure is known to allow enhanced collector transport, facilitating higher current cutoff frequencies at lower current densities and junction temperatures compared to traditional single heterojunction structures. The performance of a 0.25x3 mu m(2) pseudomorphic heteojunction bipolar transistors achieves peak f(T) of 710 GHz (f(MAX)=340 GHz) at a collector current density of 20 mA/mu m(2). The same device achieves a f(T)/f(MAX) of 540/407 GHz at a reduced current density of 7.5 mA/mu m(2). The epitaxial structure employs a 12.5 nm strained InGaAs base and 55 nm InGaAs collector, and exhibits a beta of 115 and breakdown voltage of BVCEO=1.75 V. (c) 2005 American Institute of Physics.